Growth dynamics of faceted Al13Fe4 intermetallic revealed by high-speed synchrotron X-ray quantification

Highlights: • Solidification of Al-5wt%Fe alloys was monitored via high-speed synchrotron tomography. • Formation dynamics of Al₁₃Fe₄ intermetallics were revealed. • Hole-like defects filled with aluminium melt were observed within the intermetallics. • Oriented particle attachment as a potential growth hypothesis of the Al₁₃Fe₄ intermetallics was proposed. -- Abstract: High-speed synchrotron tomography was used to investigate the nucleation and growth dynamics of Al₁₃Fe₄ intermetallic during solidification of an Al-5wt%Fe alloy, providing new insights into its formation process. The majority of Al₁₃Fe₄ intermetallics nucleated near the surface oxide of the specimen and a few nucleated at Al₁₃Fe₄ phase. Al₁₃Fe₄ crystals grew into a variety of shapes, including plate-like, hexagonal tabular, stair-like and V-shaped, which can be attributed to the crystal structure of this compound and its susceptibility to twinning. Hole-like defects filled with aluminium melt were observed within the intermetallics. Oriented particle attachment mechanism was proposed to explain the formation of the Al₁₃Fe₄ intermetallic, which needs further experiments and simulation to confirm.